There is currently a big interest in topological superconductors (TSs) with spinless \(p\) -wave pairing, fueled by the special properties that have been predicted for the Majorana bound states (MBSs) they host [1]}, [2]}, [3]}, [4]}, [5]}, [6]}. Two MBSs together encode a single fermionic state which is fixed at zero energy if the MBSs remain well separated. The state is non-local in the sense that no local measurement, i.e. coupling only to one MBS in the pair, can detect whether the fermionic state is empty or full. A system with \(N\)  well-separated MBSs has a \(2^{N/2}\) -fold degenerate ground state, where no local measurement can distinguish between the different ground states and no local perturbation can cause decoherence, unless it changes the particle number or involves excitations above the superconducting gap. This property provides topological protection against local noise sources. In addition, MBSs are non-abelian anyons, meaning that the exchange of two MBSs (so-called braiding) leads to nontrivial rotations within the degenerate ground state manifold [7]}, [8]}, [9]}, [6]}. This rotation is independent of the details of the exchange operation and thus allows error-free manipulation of the quantum state. The combination of protected storage and protected manipulation of quantum information forms the foundation for topological quantum computing schemes [11]}. On a more fundamental level, the non-local and non-abelian nature of MBSs represents a fascinating new aspect of quantum physics that is unique to systems with a topological degeneracy.
